Dyeing of polyolefins



United States Patent 01 ifice 3,533,731 Patented Oct. 13, 1970 3,533,731DYEING F POLYOLEFINS Albert J. Shmidl, Crosby, and Leroy C. Jennings,Baytown, Tex., assignors to Esso Research and Engineering Company NoDrawing. Filed June 25, 1965, Ser. No. 467,124

Int. Cl. D06p 3/00 US. Cl. 8--176 9 Claims ABSTRACT OF THE DISCLOSUREThe present invention relates to the dyeing of polyolefins. Moreparticularly, the present invention relates to a method of improving thedye uptake of a polyolefin containing dyesites and to a composition anda fiber produced therefrom which is surprisingly susceptible totreatment by acid, dispersed and premetallized dyes. More specifically,the present invention relates to the pretreatment of a dyeablepolyolefin fiber by contact with a penetrant so as to produce a polymerfiber which is more susceptible to treatment with the dyeing materialsin an aqueous dyebath. The present invention is also applicable todyeing the surface of large, molded artic es.

One of the objectives of the polyolefin industry has been to producefibers which are susceptible to treatment in the same manner ascompeting fibers when used in woven goods. The commercial practice isfor the raw fibers to be spun and woven before being submitted to adyebath, so that a woven fabric is first obtained prior to dyeing. Ifthe results of the dyebath are unsatisfactory for any reason, the fabriccan be bleached and redyed by the manufacturer.

If polyolefins are to compete in the market with natural and syntheticfibers, they must be prepared in such a manner as to be susceptible todyeing and bleaching as outlined above.

Polyolefins contain only hydrogen and carbon and thus provide nonaturally occurring dyesites for retaining a dye in the polymer. It hasbeen proposed that certain pigments be blended with the polyolefin priorto spinning, so that a deep color could be introduced throughout thefiber. This, however, has the disadvantage of making it impossible forthe dyer to bleach and redye the fabric, since the pigments within thefiber cannot be bleached.

There are several ways in which dyesites can be placed inside thepolymer fiber. First, dyesites can be incorporated by copolymerizationof a material with the monomer in order to incorporate the dyesite intothe structure of each polymer chain. A second manner in which thedyesite can be incorporated is by physically blending with thehomopolymer a material which does contain dyesites. A third manner ofincorporating dyesites within a polyolefin fiber is by graftpolymerization, such as the polymerization of styrene and maleicanhydride upon the chain of a polypropylene homopolymer.

The net result of all of these attempts to introduce reactive dyesitesinto the polyolefin itself is to distribute dyesites throughout thefiber. From the standpoint of economics, it is usually desirable to keepthe concentration of these dyesites at a practical minimum. Wherenitrogen is utilized as the dyesite, the nitrogen concentration byweight should usually be from .05 to 0.5 wt. percent. Nitrogen levelsabove 0.5 wt. percent can be used, but are not as economicallyattractive as the lower levels. At these low concentrations, there is areal problem involved in attempting to reach the dyesites with the dyein its aqueous dyebath. Only a small portion of the dyesites will appearat the surface of the fiber, and those which are internal of the fibercannot be contacted unless the dye itself penetrates into the fiber.

The present invention is based on the discovery that,

by dipping or spraying a dyeable polyolefin fiber with a penetrant whichdissolves in the polymer, the susceptibility of the dyeable fiber toacid, dispersed and premetallized dyes is greatly improved.

It is believed that the penetrant softens the noncrystalline area of thepolymer fiber, and allows the penetration of the dye into thenoncrystalline area to give a deep dyeing of the fiber. The penetrantalso may act as a dispersion breaker in order to transfer thepremetallized dye and dispersed dye from the aqueous bath onto thesurface of the fiber itself. Thus, in a twofold manner, the penetrantpretreatment aids and assists in transferring the dye into contact withthe dyesites both on the surface of and within the inerior of a dyeablepolyolefin fiber.

Before proceeding to a specific discussion of the manner in which thepresent invention is carried out, and the characteristics of the productthereof, it should be understood that the following terms wherever usedin the present application have the meanings set forth below:

The term fiber shall mean a filament, drawn or undrawn, in the'form ofdiscrete filaments, yarn, or woven fabric material.

The term polyolefin shall mean a solid hydrocarbon polymer, stabilizedor unstabilized, containing poly-a-olefins, such as polyethylene,polypropylene, polyisobutene, poly-l-butene, etc.; polydiolefins, suchas poly-1,4-butadiene, etc.; and other polymers, such as polystyrene,etc., either as the homopolymer, as a copolymer with adyesite-containing material, as a blend of homopolymers (for example,polyethylene and polypropylene), as an olefinic copolymer, such asethylene-propylene random copolymer, ethylene-propylene block copolymer,etc., including ethylene-propylene rubber.

The term dyesites refers to a reactive portion of the polymer which aidsin retaining the dye to be used, and is preferably an amino nitrogen.

The term dyesite additive refers to a material containing dyesites whichis blended with the homopolyolefin in order to provide dyesites.

The term penetrant shall mean a normally liquid hydrocarbon capable ofdissolving into at least the surface portion of a dyeable polyolefin toaid in conducting a dye into the body of the polyolefin, and ofsufiiciently low volatility that at least an effective amount willremain dissolved in the dyeable polyolefin under dyeing conditions.

The term dye is used as inclusive of acidic, dispersed and premetallizeddyes. The premetallized dye is preferred.

The term dyeable polyolefin shall refer to those materials describedbelow.

TYPES OF DYEABLE POLYOLEFINS The polyolefins to which the presentinvention is particularly directed are those which basically containonly hydrogen and carbon, such as polyethylene, polypropylene,ethylene-propylene copolymers, polyisobutene, polyisoprene, etc. As suchthey are not dyeable, since they contain no dyesites. Dyesites may bechemically incorporated by copolymerizing the olefin monomers with 3small amounts of dyesite-containing monomers. That is, usingpolypropylene as an example, both propylene and a dyesite-containingmonomer (such as an alkenyl amine) may be introduced into thepolymerization zone to obtain a polymer which has dyesites as part ofthe polymer structure. This type of dyeable polypropylene is exemplifiedby a propylene-N,N-diisopropyl-7-octeny1amine copolymer containing 0.06wt. percent nitrogen. Alternatively, the dyesite-containing monomer maybe grafted onto the polypropylene after polymerization, as exemplifiedby polypropylene with polyvinylpyridine en grafted thereupon. Othervariants include physical blends of polymers (such as polypropylene)with materials containing dyesites, such as polymers containing reacteddyesites (similar to those described above) or with other organic orinorganic materials which provide such dyesites. The relativeproportions in these blends will depend on a balancing of a number offactors, including the effect of the blendstock on polymer properties,intensity of color required, efficiency of dyesite additive, etc. Theparticular additive to be used will depend on the type of dye to beemployed, the use to which the dyed material will be put, etc.

All of these modified fibers are referred to herein as dyeablepolyolefins. The process of the present invention is equally applicableto films and fibers, drawn and undrawn, which are made from resins ofthe dyeable polyolefins.

PENETRANTS The dyeable polyolefin is treated with a penetrant asaforesaid. The penetrant can be alkyl-substituted or unsubstituted oneand two-ring naphthenes, and partially ring-unsaturated derivativesthereof, such as Decalin, Tetralin, cyclohexane, cyclohexene, and loweralkyl-substituted derivatives thereof. If substituted derivatives areemployed, they preferably should have no more than three substituentalkyl groups of three or less carbon atoms each or the hydrocarbon willtend to be a solid at moderate temperatures.

Other penetrants are parafiins and linear olefins, normal or branched,having from 6 to 12 carbon atoms, and aromatic hydrocarbons,unsubstituted or lower alkyl substituted, having one or two rings andhaving a total of from 6 to 12 carbon atoms. Xylenes, in particular,should be suitable.

Decalin, Tetralin, cyclohexane, and cyclohexene are preferred aspenetrants.

The penetrants can be used alone or in admixture with one another.Diluents can also be employed, so long as the diluent has no deleteriouseffect on the polymer or the dyeing operations. Less effectivepenetrants (such as n heptane) can be used as diluents for moreeffective penetrants (such as decalin).

Chlorinated hydrocarbon compounds are to be avoided and should not beused either as penetrants or as diluents, since the chlorine has adeleterious effect on the oxidative stability and color stability of thepolymer.

High molecular weight plasticizers and viscous white oils should also beavoided.

The amount of penetrant to be used is based upon the weight of dyeablepolyolefin involved. In a thin film or fiber, the entire polyolefin isinvolved and the total weight is used as a basis. Where a molded objectis to be dyed, however, the amount of penetrant cannot be based on thetotal weight but can easily be determined by trial and error in eachcase.

For films and fibers, the penetrant content of the film or fiber beforedyeing should be from 0.5 to 10 parts by weight per hundred parts byweight of dyeable polyolefin. Preferably, about 3 to parts by weight ofpenetrant are employed for each hundred parts of dyeable polyolefin,since some of the penetrant may be lost by vaporization under theelevated temperature conditions encountered in the dyebath. The dyedfiber will usually contain from 4 0.01 to 1 part by weight of penetrantper hundred parts of dyeable polyolefin.

When used with a diluent, the penetrant should be present in aconcentration of at least 10% by volume. In some cases it may bepreferred to use the penetrant with no diluent. For example, it ispreferred to use cyclohexane with no diluent.

The penetrant may also be employed in a water emulsion, wherein thepenetrant comprises a concentration of from 10 to 50 wt. percent in anoil-continuous phase. The emulsion is obtained and maintained byemploying suitable well-known surfactant emulsifiers.

DYES

Many dyes are suitable for dyeing the treated polymer.

Acidic dyes include Erio Anthracene Blue ZGC (CI 62055) and EricAnthracene Rubine 3GP.

Disperse dyes include Carbolan Green 5G5, Celenthrene Blue 26 (CI62500), and Carbolan 2GS.

Premetallized dyes include Vialon Orange RR, Vialon Orange R, IrgalanYellow GL, and Vialon Violet RR. The structure of premetallized dyes,particularly the Irgalan dyes, has been discussed in detail by Schettyin The Irgalan Dyes-Neutral-dyeing Metal-Complex Dyes, published in theDecember 1955 issue of the Journal of the Society of Dye Chemists. Otherwell-known premetallized dyes are disclosed in the Color Index, such asAtalan Pink BN (CI 18810) and Supralan Yellow NR (CI 18690), both ofwhich are chromium complexes, and Capracyl Yellow RN (CI 11700) which isa cobalt complex.

Each dye is employed in accordance with the instructions provided by themanufacturer. Generally, they are all used in a hot aqueous dyebath. Thepremetallized dyes are employed in an aqueous dispersion, being in aconcentration of 1.0 to 5.0 wt. percent OWF (i.e., based on the weightof the fiber to be dyed in that bath). An emulsifying agent such asTriton X- is commonly employed to maintain the dispersion. The dyebathis kept at a temperature of 100 F. to 212 F., and the fabric iscontacted with the dyebath for a period of time determined by the typeof fiber employed in the fabric, the type of dye employed, the depth ofcolor desired, the dye concentration, etc. The pH will vary, dependingon the particular dye being employed.

PRETREATMENT OF POLYMER The dyeable polyolefin, preferably in the formof a fabric woven from drawn fibers thereof, is contacted in apretreatment zone with a penetrant under conditions chosen to dissolvefrom 0.5 to 10 parts by weight of penetrant in every 100 parts by weightof polyolefin fiber, preferably from 4 to 8 parts by weight. Thiscontacting can be accomplished by spraying or immersing the fabric withthe chosen penetrant.

Where the penetrant is to be sprayed upon the fabric, the penetrant isemployed at a temperature of 40 F. to F. (preferably at 75 F.), and at aspray treat rate of from 0.5 to 20 (preferably 10) pounds of penetrantper 100 pounds of fabric. Above 15 pounds per 100 pounds the penetrantmerely runs immediately off of the fabric. The fabric may be shaken,blotted, or wiped to remove excess penetrant after allowing from 5 to 60minutes for penetration into the fibers. Alternatively, the fabric maybe hung and allowed to drip until the excess penetrant has been removed.The excess can also be removed by centrifuging, pressing or othersuitable means to lower the amount of penetrant in the fiber to thedesired amount.

If the fabric is immersed in the penetrant, a temperature of 40 F. to150 F. (preferably F.) is maintained and the fabric residence time inthe penetrant bath is from 5 to 60 minutes. Atmospheric pressure ispreferred, but may suitably range from 0 to 50 p.s.i.g.

7 COPOLYMERS Examples 11 2 The fibers used in these examples wereprepared from a propylene: N,N-diisopropyl-7-octenyl amine copolymer,containing various levels of nitrogen. They were dyed with disperseddyes such as Carbolan Brilliant Green 568 and Carbolan Brilliant Blue2GS, premetallized dyes, such as Irgalan Yellow GL, Vialon Fast VioletRR, Vialon Fast Orange R and Vialon Fast Orange RR, and acid dyes suchas Erio Anthracene Brilliant Blue 2GC. At lower nitrogen levels, amarked increase in dye uptake was observed. At nitrogen levels aboveabout 3%, sufficient dyeability was obtained without penetrantpretreatment, but the physical properties of the fiber were lessdesirable.

Examples 1-4 illustrate the use of an acid dye.

Example 1 A fiber was prepared from the copolymer containing 0.04 wt.percent nitrogen. It was dyed with Erio Anthracene Brilliant Blue 2GC,both with and without a pre treatment With Decalin. TheDecalinpretreated sample was markedly superior to the untreated samplein dye uptake.

Example 2 A fiber diameter was prepared from the copolymer containing0.06 wt. percent nitrogen. It was dyed with Erio Anthracene BrilliantBlue 2GC both with and without a pretreatment with Decalin. TheDecalin-pretreated sample was markedly superior to the untreated samplein dye uptake.

Example 3 The dyeing run of Example 2 was repeated, substituting for theDecalin a penetrant consisting of 25 'vol. percent Decalin and 75 vol.percent n-heptane. Again, the treated sample was markedly superior tothe untreated sample in dye uptake.

Example 4 A fiber diameter was prepared from the copolymer having 0.08wt. percent nitrogen. It was dyed with Erio Anthracene Brilliant 2GCboth with and without Decalin pretreatment. The Decalin-pretreatedsample was markedly superior to the untreated sample in dye uptake.

Examples 5-8 illustrate the use of a dispersed dye.

Example 5 The same fiber as in Example 2, containing 0.06 wt. percentnitrogen, was dyed with Carbolan Brilliant Green SGS both with andwithout Decalin pretreatment. The Decalin-pretreated sample was markedlysuperior to the untreated sample in dye uptake.

Example 6 The dyeing run of Example 5 was repeated, substituting for theDecalin a penetrant consisting of vol. percent Decalin and 75 vol.percent n-heptane. The pretreated sample was markedly superior to theuntreated sample in dye uptake.

Example 7 The same fiber as in Example 2, containing 0.06 wt. percentnitrogen, was dyed with Carbolan Brillant Blue 2GS both with and withoutDecalin pretreatment. The Decalin-pretreated sample was markedlysuperior to the untreated sample in dye uptake.

Example 8 The dyeing run of Example 7 was repeated, substituting for theDecalin a penetrant consisting of 25 vol. percent Decalin and 75 vol.percent n-heptane. The pretreated sample was markedly superior to theuntreated sample in dye uptake.

Examples 9-12 illustrate the use of a pre-metallized dye.

Example 9 The same fiber as in Example 2, containing 0.06 wt. percentnitrogen, was dyed with Irgalan Yellow GL both with and without Decalinpretreatment. The Decalinpretreated sample was markedly superiod to theuntreated sample in dye uptake.

Example 10 The dyeing run of Example 9 was repeated, substituting forthe Decalin a penetrant consistng of 25 vol. percent Decalin and vol.percent n-heptane. The pretreated sample was markedly superior to theuntreated sample in dye uptake.

Example 11 A fiber was prepared from the copolymer having 0.3 wt.percent nitrogen. It was dyed with Vialon Fast Violet RR both with andwithout Decalin pretreatment. The Decalin-pretreated sample was markedlysuperior to the untreated sample in dye uptake.

Example 12 The same fiber as in Example 11, containing 0.3 wt. percentnitrogen, was dyed with Vialon Fast Orange R both with and withoutDecalin pretreatment. The Decalin-pretreated sample was markedlysuperior to the un treated sample in dye uptake.

BLENDS Examples 1317 The fibers used in these examples were preparedfrom two types of polymer blends. Type I is a blend of wt. percenthomopolypropylene with 10 Wt. percent of a copolymer of propylene andN,N-diisopropyl-7-octenyl amine. This first polymer blend had a nitrogencontent of 0.06 wt. percent. Type II is a blend of 97 wt. percenthomopolypropylene and 3 wt. percent polyvinyl-pyridine, giving anitrogen content of 0.4 wt. percent.

The fibers were dyed with acid dyes such as Erio Anthracene BrilliantBlue 2GC and Erio Anthracene Rubine 3GP and premetallized dyes such asVialon Fast Violet RR, Vialon Fast Orange R, Vialon Fast Orange RR,Irgalan Yellow 2RL, and Lanasyn Brown 2RL.

Comparative runs using Decalin and cyclohexene as penetrants showed ineach case a marked improvement in dye uptake when penetrant pretreatmentwas employed.

Examples 1316 illustrate the use of acid dyes.

Example 13 A fiber was prepared from the Type I blend ofhomopolypropylene and the propylene-N,N-diisopropyl-7-octenyl aminecopolymer. It contained 0.06 wt. percent nitrogen. It was dyed with ErioAnthracene Brilliant Blue 260 both with and without a pretreatment withDecalin. The Decalin-pretreated sample was markedly superior to theuntreated sample in dye uptake.

Example 14 The dyeing run of Example 13 was repeated, substituting forthe Decalin a eyclohexane penetrant. The treated sample was markedlysuperior to the untreated sample in dye uptake.

Example 15 The same fiber in Example 13 was dyed with Erio AnthraceneRubine 3GP both with and without a pretreatment with Decalin. TheDecalin-pretreated sample was markedly superior to the untreated samplein dye uptake.

Example 16 The dyeing run of Example 15 was repeated, substituting forthe Decalin a eyclohexane penetrant. The treated sample was markedlysuperior to the untreated sample in dye uptake.

Examples 17-26 illustrate the use of premetallized dyes.

Example 17 The same fiber as in Example 13 was dyed with Vialon FastViolet RR both with and without Decalin pretreatment. TheDecalin-pretreated sample was markedly superior to the untreated samplein dye uptake.

Example 18 The same fiber as in Example 13 was dyed with Vialon FastOrange RR both with and without Decalin pretreatment. TheDecalin-pretreated sample was markedly superior to the untreated samplein dye uptake.

Example 19 The same fiber as in Example 13 was dyed with Irgalon Yellow2RL both with and without a Decalin pretreatment. The Decalin-pretreatedsample was markedly superior to the untreated sample in dye uptake.

Example 20 The dyeing run of Example 19 was repeated, substitutingcyclohexane for the Decalin penetrant. The pretreated sample wasmarkedly superior to the untreated sample in dye uptake.

Example 21 s The same fiber as in Example 13 was dyed with Vialon FastOrange R both with and without Decalin pretreatment. TheDecalin-pretreated sample was markedly superior to the untreated samplein dye uptake.

Example 22 The dyeing run of Example 21 was repeated, substitutingcyclohexane for the Decalin penetrant. The pretreated sample wasmarkedly superior to the untreated sample in dye uptake.

Example 23 The same fiber as in Example 13 was dyed with Lanasyn Brown2RL both with and Without Decalin pretreatment. The Decalin-pretreatedsample was markedly superior to the untreated sample in dye uptake.

Example 24 The dyeing run of Example 23 was repeated, using Vialon FastViolet RR as the dye. The pretreated sample was markedly superior to theuntreated sample in dye uptake.

Example 25 A fiber was prepared from the Type II blend ofhomopolypropylene and polyvinylpyridine. It contained 0.4 wt. percentnitrogen. It was dyed with Vialon Fast Orange RR both with and without aDecalin-pretreatment. The Decalin-pretreated sample was markedlysuperior to the untreated sample in dye uptake.

Example 26 The same fiber as in Example 25 was dyed with Vialon FastViolet RR both with and without Decalin pretreatment. TheDecalin-pretreated sample was markedly superior to the untreated samplein dye uptake.

Example 27 illustrates the use of an acid dye.

Example 27 The same fiber as in Example 25 was dyed with Erio AnthraceneBrilliant Blue ZGC both with and without a Decalin pretreatment. TheDecalin-pretreated sample was markedly superior to the untreated samplein dye uptake.

GRAFI POLYMERS Examples 28-30 The fibers used in these examples wereprepared from a graft copolymer of polyvinylpyridine on ahomopolypropylene backbone. Various levels of nitrogen were obtained.The graft copolymers were dyed with a dispersed dye-Celenthrene FastBlue 2G.

Example 28 A fiber was prepared from a graft copolymer as de-' scribedabove, having a nitrogen content of 0.04 wt. percent. It was dyed withCelenthrene Fast Blue 2G, both with and without a Decalin pretreatment.The Decalinpretreated sample was markedly superior to the untreatedsample in dye uptake.

Example 29 Example 30 A fiber was prepared from a graft copolymer asdescribed above, having a nitrogen content of 0.35 wt. percent. It wasdyed with Celenthrene Fast Blue 26, both with and without a Decalinpretreatment. The Decalinpretreated sample was markedly superior to theuntreated sample in dye uptake.

As can be seen from the table above, the susceptibility of the fibersamples to dyeing is increased by the penetrant pretreatment.Particularly, the premetallized dyes show an outstanding susceptibilityto the Decalin treated dyeable polypropylene as compared to theuntreated 'po1ypropylene. Further, the use of a cyclohexane penetranthas been shown to be advantageous.

Having disclosed the invention and having set forth preferred modes ofpracticing the same, what we desire to cover by Letters Patent should belimited not by the specific examples herein given, but rather only bythe appended claims.

We claim:

1. A method of dyeing a fiber made of a polyolefin which containsnitrogen dyesites, which comprises in a pretreating zone, contactingparts by weight of said shaped article with a penetrant chosen from thegroup consisting of Decalin, Tetralin, cyclohexane and cyclohexene,under conditions chosen to leave from 0.5 to 10 parts by weight of saidpenetrant dissolved at the surface of said polyolefin,

said conditions including a temperature within the range from 40 F. toF., and thereafter, in a dyeing zone, treating said shaped article underdyeing conditions with a dye chosen from the group consisting of aciddyes, dispersed dyes and premetallized dyes.

2. A method in accordance with claim 1 wherein the polyolefin ispolypropylene.

3. A method in accordance with claim 2 wherein the penetrant is Decalin,and from 4 to 8 parts by weight of Decalin are used per hundred parts byweight of polypropylene.

4. A method in accordance with claim 3 wherein the dye is apremetallized dye.

5. A method in accordance with claim 1 wherein the pretreatmentcontacting is carried out by immersing the polyolefin in the penetrantat a pressure of 0 to 50 p.s.i.g. and for a time from 5 to 60 minutes.

and the dyeing step is carried out within 24 hours after the pretreatingstep is completed.

6. A method in accordance with claim 5 wherein the polyolefin ispolypropylene.

7. A method in accordance with claim 6 wherein the penetrant is Decalin.

3,533,731 1 1 1 2 8. A method in accordance with claim 7 wherein theFOREIGN PATENTS A i iift h d i c i mce with claim 8 wherein from 9211193/1963 Great i i 4 to 8 parts by weight of Decalin are used per hundred940,716 10/1963 Great Bntam' parts by Weight of 5 GEORGE F. LESMES,Primary Examiner Referen s Cited B. BETTIS, Assistant Examiner UNITEDSTATES PATENTS 2,329,113 4/1953 Wehr. US 3,123,146 4/1964' Bianco et a1.10 3 94, 130; 260-33.6, 33.1, 373, 395, 397

